A semiconductor device is constantly required to be reduced in size and weight. In order to realize the size reduction, a structure of efficiently cooling a semiconductor element is inevitable. Particularly, development of a direct cooling structure in which a semiconductor element is joined directly on a cooling fin to directly cool the semiconductor element has been promoted. Especially, development of a fin-integrated semiconductor device (e.g., Patent Document 1) and a fin-and-cooler-integrated semiconductor device (e.g., Patent Documents 2 to 5) has been actively conducted.